<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>响应式</title>
    <style>
        @media only screen and (max-width:374px) {
            html {
                font-size: 86px;
            }
        }
        @media only screen and (min-width:375px) and (max-width: 414px) {
            html {
                font-size: 100px;
            }
        }
        @media only screen and (min-width:415px) {
            html {
                font-size: 110px;
            }
        }
        body {
            font-size: 0.16rem;
        }
        #div1 {
            width: 1rem;
            background-color: #ccc;
        }

    
    </style>
</head>
<body>
    <div id="div1">
        this is div 
    </div>
</body>
</html>